Technical￿training. Product￿information. F48￿Powertrain

BMW￿Service General￿information

Symbols￿used

The￿following￿symbol￿is￿used￿in￿this￿document￿to￿facilitate￿better￿comprehension￿or￿to￿draw￿attention to￿very￿important￿information:

Contains￿important￿safety￿information￿and￿information￿that￿needs￿to￿be￿observed￿strictly￿in￿order￿to guarantee￿the￿smooth￿operation￿of￿the￿system.

Information￿status￿and￿national-market￿versions

BMW￿Group￿vehicles￿meet￿the￿requirements￿of￿the￿highest￿safety￿and￿quality￿standards.￿Changes in￿requirements￿for￿environmental￿protection,￿customer￿benefits￿and￿design￿render￿necessary continuous￿development￿of￿systems￿and￿components.￿Consequently,￿there￿may￿be￿discrepancies between￿the￿contents￿of￿this￿document￿and￿the￿vehicles￿available￿in￿the￿training￿course.

This￿document￿basically￿relates￿to￿the￿European￿version￿of￿left-hand￿drive￿vehicles.￿Some￿operating elements￿or￿components￿are￿arranged￿differently￿in￿right-hand￿drive￿vehicles￿than￿shown￿in￿the graphics￿in￿this￿document.￿Further￿differences￿may￿arise￿as￿a￿result￿of￿the￿equipment￿specification￿in specific￿markets￿or￿countries.

Additional￿sources￿of￿information

Further￿information￿on￿the￿individual￿topics￿can￿be￿found￿in￿the￿following:

• Owner's￿Handbook • Integrated￿Service￿Technical￿Application.

Contact:￿conceptinfo@.de

©2015￿BMW￿AG,￿Munich

Reprints￿of￿this￿publication￿or￿its￿parts￿require￿the￿written￿approval￿of￿BMW￿AG,￿Munich

The￿information￿contained￿in￿this￿document￿forms￿an￿integral￿part￿of￿the￿technical￿training￿of￿the BMW￿Group￿and￿is￿intended￿for￿the￿trainer￿and￿participants￿in￿the￿seminar.￿Refer￿to￿the￿latest￿relevant information￿systems￿of￿the￿BMW￿Group￿for￿any￿changes/additions￿to￿the￿technical￿data.

Information￿status:￿June￿2015 BV-72/Technical￿Training F48￿Powertrain Contents

1. Drive￿Variants...... 1 1.1. Model...... 2 1.2. Engine￿designation...... 3 1.2.1. Engine￿identification...... 3

2. Cooling￿System...... 4 2.1. Cooling￿module...... 4

3. Automatic￿...... 6 3.1. Designation...... 8 3.2. Function￿diagram...... 9 3.3. Ratios...... 10 3.4. Direct￿shifting...... 11 3.5. Coasting￿in￿idle...... 11 3.6. Launch￿Control...... 11 3.6.1. Activation￿of￿launch￿control...... 12 3.7. ConnectedShift...... 12 3.7.1. Characteristics￿and￿availability...... 12 3.8. Notes￿for￿Service...... 13 3.8.1. Special￿tools...... 13 3.8.2. Manually￿unlocking￿the￿drive￿position￿lock...... 13 3.8.3. Available￿replacement￿parts...... 14

4. xDrive...... 15 4.1. Introduction...... 15 4.1.1. Comparison￿of￿all-wheel￿drive￿systems...... 15 4.2. System￿components...... 17 4.2.1. Angular￿gearbox...... 18 4.2.2. Propeller￿shaft...... 20 4.2.3. Rear￿axle￿differential...... 23 4.2.4. System￿wiring￿diagram...... 26 4.3. Function...... 27 4.3.1. Longitudinal￿torque￿distribution...... 27 4.3.2. Operating￿strategy...... 29 4.4. Notes￿for￿Service...... 30

5. Output￿Shaft,￿Front...... 31

F48￿Powertrain 1.￿Drive￿Variants

The￿F48￿is￿available￿with￿xDrive.￿The￿following￿graphic￿shows￿the￿layout￿of￿that￿version.

F48￿Drive

In￿the￿F48￿a￿completely￿new￿drive￿unit￿is￿used,￿which￿fits￿perfectly￿with￿the￿spatial￿functional￿concept of￿the￿BMW X1￿thanks￿to￿its￿model-specific￿design.

The￿new￿BMW￿X1￿xDrive28i￿is￿one￿of￿the￿first￿vehicles￿of￿BMW￿which￿will￿be￿driven￿by￿the￿brand￿new 4-cylinder￿engine.￿It￿is￿a￿part￿of￿the￿newly￿developed￿modular￿engine￿family.￿It￿is￿a￿lightweight,￿powerful and￿economical￿engine,￿which￿is￿equipped￿with￿BMW￿TwinPower￿Turbo￿technology.

Special￿features

• New￿4-cylinder￿engines • Engine￿with￿transverse￿mounting • xDrive • All￿engines￿satisfy￿the￿exhaust￿emission￿standards￿SULEV

1 F48￿Powertrain 1.￿Drive￿Variants

The￿following￿list￿shows￿the￿advantages￿of￿the￿different￿drive￿concepts￿(for￿vehicles￿with￿a￿front engine):

Front-wheel￿drive Rear-wheel￿drive

• The￿drive￿unit￿is￿comparatively￿compact • Small￿turning￿circle￿possible,￿as￿no and￿is￿integrated￿between￿the￿axle rear￿view￿of￿the￿drive￿required￿with￿the mounting,￿steering￿and￿footwell. steered￿front￿axle. • Large￿and￿variable￿spatial￿offering • No￿annoying￿drive￿influences￿in￿the thanks￿to￿reduction￿or￿deletion￿of steering. the￿transmission￿tunnel￿and￿rear￿axle • Good￿power￿transmission￿to￿the differential. roadway￿during￿acceleration,￿as￿the • Weight￿and￿cost￿reductions,￿due￿to driven￿axle￿is￿loaded￿(primarily￿when deletion￿of￿propeller￿shaft￿and￿rear￿axle driving￿off￿on￿inclines). differential,￿as￿well￿as￿integration￿of￿the • Balanced￿axle-load￿distribution differential￿in￿the￿transmission. possible. • Good￿traction￿on￿smooth￿roadway, • Excellent￿dynamic￿cornering￿behavior. independent￿of￿the￿load￿status￿of￿the vehicle,￿due￿to￿higher￿axle￿load￿at￿the driven￿axle. • Reasonable￿behavior￿in￿the￿event of￿a￿head-on￿collision￿(engine￿and transmission￿intrude￿the￿passenger compartment￿less).

1.1.￿Model

The￿following￿model￿is￿offered￿for￿the￿market￿introduction￿of￿the￿F48:

Model BMW￿228i Engine B46A20O0 Cylinders 4 Displacement [cm³] 1998 Power [kW￿(HP)] 170￿(231) Torque [Nm] 350 Automatic￿transmission GA8F22AW Manual￿gearbox –

2 F48￿Powertrain 1.￿Drive￿Variants

1.2.￿Engine￿designation

In￿the￿technical￿documentation,￿the￿engine￿designation￿is￿used￿to￿ensure￿unambiguous￿identification of￿the￿engine.￿In￿the￿following￿table￿the￿engine￿designations￿used￿in￿the￿F48￿are￿explained.

Position Meaning Index Explanation 1 Engine￿developer B BMW￿Group 2 Engine￿type 4 4-cylinder￿in-line￿engine 3 Change￿to￿the￿basic 8 Turbo-Valvetronic￿direct￿injection￿(TVDI) engine￿concept 4 Working￿method￿or￿fuel A Petrol￿engine,￿transversal￿installation and￿installation￿position 5 + 6 Displacement￿in￿1/10 liter 20 2.0 liters￿displacement 7 Performance￿class U Lower M Middle O Upper 8 Revision￿relevant￿to 0 New￿development approval 1 – 9 Redesign

1.2.1.￿Engine￿identification

The￿7-digit￿engine￿identification￿is￿on￿the￿crankcase.￿The￿first￿6￿digits￿of￿the￿engine￿identification￿are deduced￿from￿the￿engine￿type.￿Only￿the￿seventh￿digit￿is￿different.￿With￿the￿engine￿identification￿the test￿number￿of￿the￿type￿approval￿certification￿is￿located￿at￿the￿7th￿position.

3 F48￿Powertrain 2.￿Cooling￿System

2.1.￿Cooling￿module

F48￿cooling￿system￿for￿B48￿engine

Index Explanation 1 Expansion￿tank 2 Electric￿coolant￿pump 3 Cooling￿module 4 Cooling￿module￿bearing,￿top 5 Cooling￿module￿bearing,￿bottom 6 Coolant￿pump 7 Engine￿oil-to-coolant￿heat￿exchanger

A￿frameless￿cooling￿module￿is￿installed￿in￿the￿F48.￿This￿is￿made￿possible￿by￿a￿concept￿with￿different separation￿points￿between￿radiator￿and￿charge￿air￿cooler,￿using,￿joint￿interfaces￿for￿body￿and￿coolant hoses.

In￿vehicles￿with￿an￿automatic￿transmission,￿a￿transmission￿oil-coolant-heat￿exchanger￿is￿also￿flange- mounted￿at￿the￿transmission.￿This￿is￿supplied￿with￿coolant￿via￿the￿crankcase￿and￿adapted￿coolant hoses.

In￿the￿following￿diagram￿you￿see￿the￿connection￿of￿the￿cooling￿module￿at￿the￿cooling￿circuit￿using￿the example￿of￿the￿B46￿engine.

4 F48￿Powertrain 2.￿Cooling￿System

F48￿cooling￿circuit,￿B46￿engine

Index Explanation 1 Radiator 2 Electric￿fan 3 Electric￿coolant￿pump 4 Thermostat 5 Coolant￿pump 6 Exhaust￿turbocharger 7 Heat￿exchanger 8 Coolant￿shutoff￿valve 9 Transmission￿oil-to-coolant￿heat￿exchanger 10 Engine￿oil-to-coolant￿heat￿exchanger 11 Expansion￿tank

5 F48￿Powertrain 3.￿Automatic￿Transmission

F48￿automatic￿transmission

In￿the￿F48￿a￿new￿8-speed￿automatic￿gearbox￿GA8F22AW￿are￿used:

Designation Gears Transferable￿torque Use￿in￿engine GA8F22AW 8-speed 350 Nm B46A20O0

6 F48￿Powertrain 3.￿Automatic￿Transmission

The￿excellent￿efficiency￿was￿able￿to￿be￿achieved￿by￿the￿following￿measures:

• Small￿oil￿pump • Lower￿transmission￿oil￿main￿pressure • Optimal￿lubricating￿oil￿quantity • Transmission￿oil￿with￿low￿viscosity • Large￿steering￿axis￿inclination • Very￿accurate￿control￿of￿the￿multidisc￿converter￿lockup￿clutch￿at￿low￿loads by￿three-line￿activation • Designed￿for￿automatic￿engine￿start-stop￿function￿(there￿is￿also￿an￿electric￿oil pump￿in￿the￿hydraulic￿block￿in￿order￿to￿maintain￿the￿minimum￿oil￿pressure) • Designed￿for￿idle￿speed￿coasting

Good￿ride￿and￿shifting￿comfort￿was￿able￿to￿be￿realized￿with￿the￿following￿measures:

• Newly￿developed￿mechanical￿torsional￿vibration￿damper • Efficient￿hydraulics￿with￿new￿valves • Efficient￿clutch￿and￿brake￿control • Excellent￿direct￿shifting￿capability￿(multiple￿downshifts,￿explained￿in￿the￿following)

In￿the￿Sport￿program￿and￿Manual￿mode￿the￿shift￿point￿and￿shift￿speed￿have￿a￿more￿sporty￿dimension.

F48￿EGS,￿8-speed￿automatic￿transmission

The￿electronic￿transmission￿control￿is￿located￿in￿the￿F48￿on￿the￿transmission￿housing.￿The￿selector lever￿position￿switch￿is￿designed￿as￿a￿hall￿effect￿sensor￿and￿integrated￿in￿the￿EGS.￿The￿outer￿wiring between￿EGS,￿selector￿lever￿position￿switch￿and￿transmission￿was￿discontinued,￿whereby￿the susceptibility￿to￿faults￿was￿also￿reduced.

7 F48￿Powertrain 3.￿Automatic￿Transmission

3.1.￿Designation

The￿transmission￿designation￿in￿the￿technical￿documentation￿allows￿it￿to￿be￿uniquely￿identified. In￿frequent￿cases,￿however,￿only￿a￿short￿designation￿is￿used.￿This￿short￿form￿is￿used￿so￿the transmission￿can￿be￿assigned￿to￿a￿transmission￿family.￿The￿GA8HP￿transmission￿family,￿consisting of￿several￿transmissions￿such￿as￿the￿GA8HP45Z,￿the￿GA8HP70Z￿and￿the￿GA8HP90Z,￿is￿often mentioned.

Position Meaning Index Explanation 1 Designation G Transmission 2 Type￿of￿transmission A Automatic￿transmission 3 Number￿of￿gears 8 Eight￿forward￿gears 4 – 7* Individual HP Hydraulic￿planetary￿gear designations* L Designation￿of￿General￿Motors￿Powertrain R Designation￿of￿General￿Motors￿Powertrain 19 300 Nm￿gas￿engine F21A Designation￿of￿AISIN￿Warner 26 600 Nm 32 720 Nm 45 450 Nm (Zahnradfabrik350 Nm Friedrichshafen)700 Nm 45 900 Nm (General 390 Nm,￿4th gear￿410 Nm, Motors Powertrain) 70 90 390 8 Manufacturer A AISIN G Getrag J Jatco K GKN R General￿Motors￿Powertrain Z Zahnradfabrik￿Friedrichshafen H In-house￿part

*￿Numbers￿4￿–￿7￿serve￿for￿individual￿designation.￿A￿transmission￿variant,￿size,￿transferable￿torque￿and technical￿update￿can￿be￿represented￿here.

8 F48￿Powertrain 3.￿Automatic￿Transmission

3.2.￿Function￿diagram

Function￿diagram￿using￿the￿example￿of￿a￿6-speed￿automatic￿transmission

9 F48￿Powertrain 3.￿Automatic￿Transmission

Index Explanation B1 Brake￿band￿B1￿(blocks￿the￿front￿sun￿gear￿of￿the￿rear￿planetary￿gear￿set) B2 Brake￿clutch￿B2￿(blocks￿the￿planet￿carrier￿of￿the￿rear￿planetary￿gear￿set) C1 Drive￿clutch￿C1￿(connects￿the￿planet￿carrier￿of￿the￿front￿planetary￿gear￿set￿to the￿rear￿sun￿gear￿of￿the￿rear￿planetary￿gear￿set) C2 Drive￿clutch￿C2￿(connects￿the￿intermediate￿shaft￿to￿the￿planet￿carrier￿of￿the rear￿planetary￿gear￿set) C3 Drive￿clutch￿C3￿(connects￿the￿planet￿carrier￿of￿the￿front￿planetary￿gear￿set￿to the￿front￿sun￿gear￿of￿the￿rear￿planetary￿gear￿set)

3.3.￿Ratios

GA8F22AW Ratio,￿1st￿gear 5.25 Ratio,￿2nd￿gear 3.029 Ratio,￿3rd￿gear 1.95 Ratio,￿4th￿gear 1.457 Ratio,￿5th￿gear 1.221 Ratio,￿6th￿gear 1 Ratio,￿7th￿gear 0.809 Ratio,￿8th￿gear 0.673 Ratio,￿reverse￿gear 4.015

10 F48￿Powertrain 3.￿Automatic￿Transmission

3.4.￿Direct￿shifting

With￿the￿new￿automatic￿transmission￿of￿the￿F48,￿in￿most￿cases￿direct￿shifting￿to￿the￿desired￿gear￿is possible.￿This￿also￿applies￿if￿gears￿are￿skipped.

A￿direct￿gear￿change￿is￿always￿possible￿if￿the￿status￿has￿to￿change￿for￿one￿of￿the￿switched￿clutches or￿brakes.￿Otherwise,￿a￿two-stage￿gear￿change￿is￿performed.￿However,￿in￿general￿the￿customer￿does not￿notice￿this￿due￿to￿the￿optimized￿transmission￿control￿unit.

The￿following￿table￿shows￿the￿switched￿brakes￿and￿clutches￿for￿each￿gear￿using￿the￿example￿of￿the GA6F21AW.

Gear Brake Brake Clutch Clutch Clutch B2 B1 C2 C1 C3 N X 1 X X 2 X X 3 X X 4 X X 5 X X 6 X X Rw X X

Examples:

• Direct￿shift￿is￿possible￿from￿4th￿to￿2nd￿gear,￿as￿the￿clutch￿C1￿does￿not￿have￿to￿be￿shifted. • Direct￿shift￿is￿not￿possible￿from￿5th￿to￿2nd￿gear￿as￿both￿the￿brake￿B1￿and￿the￿clutch￿C1 have￿to￿be￿switched.

3.5.￿Coasting￿in￿idle

For￿the￿F48￿the￿"Coasting￿in￿idle￿position"￿function￿is￿available.￿Under￿certain￿prerequisites￿the￿engine is￿automatically￿disconnected￿from￿the￿transmission￿in￿gear￿selector￿switch￿position￿D.￿The￿engine runs￿here￿at￿idle￿speed.

Further￿information￿on￿"Coasting"￿is￿available￿in￿the￿product￿information￿bulletin￿"F01/F02￿LCI Displays￿and￿Operation".

3.6.￿Launch￿Control

For￿vehicles￿with￿Sports￿automatic￿transmission￿(SA 2TB),￿launch￿control￿enables￿optimal￿acceleration when￿driving￿off.￿Forced￿upshifts￿are￿also￿performed￿without￿a￿reduction￿of￿the￿engine￿torque.￿This enables￿additional￿acceleration￿during￿the￿gearshifts.

In￿order￿to￿avoid￿premature￿component￿wear,￿the￿drive-off￿with￿launch￿control￿is￿only￿available￿100 times￿over￿the￿service￿life￿of￿the￿Sports￿automatic￿transmission￿and￿cannot￿be￿reset￿by￿Service.

11 F48￿Powertrain 3.￿Automatic￿Transmission

3.6.1.￿Activation￿of￿launch￿control

Step Responsibility 1 Press￿the￿DSC button￿and￿select￿SPORT￿using￿the￿driving￿experience￿switch. –￿In￿the￿instrument￿cluster￿TRACTION￿is￿displayed￿in￿combination￿with￿SPORT. The￿indicator￿light￿DSC￿OFF￿illuminates. 2 Engage￿drive￿position S. 3 Firmly￿press￿the￿brake￿using￿the￿left￿foot. 4 Press￿the￿accelerator￿pedal￿beyond￿the￿resistance￿at￿the￿kick-down￿pressure￿point and￿hold. –￿Flag￿symbol￿appears￿in￿the￿instrument￿cluster￿and￿the￿engine￿speed￿for￿pulling away￿is￿adjusted. 5 Release￿the￿brake￿within￿3￿seconds￿and￿hold￿the￿accelerator￿pedal. –￿Vehicle￿accelerates￿optimally.

3.7.￿ConnectedShift

ConnectedShift￿uses￿navigation￿data￿for￿a￿forward-thinking￿shift￿strategy￿of￿the￿.￿If,￿for￿example,￿a￿sharp￿bend￿is￿detected,￿the￿automatic￿transmission￿shifts￿down￿early and￿the￿gear￿is￿retained￿in￿the￿bend.

The￿route￿guidance￿of￿the￿navigation￿system￿does￿not￿need￿to￿be￿activated￿for￿the￿function.￿However, the￿identification￿of￿a￿turn-off￿request,￿for￿example￿by￿the￿active￿route￿guidance￿or￿operating￿the￿turn indicator,￿helps￿to￿control￿the￿system￿more￿accurately.￿Up-to-date￿navigation￿map￿data￿also￿influences the￿control￿accuracy.

3.7.1.￿Characteristics￿and￿availability

In￿SPORT￿and￿COMFORT￿modes,￿the￿characteristics￿of￿ConnectedShift￿are￿adapted￿to￿the￿respective driving￿program,￿in￿ECO￿PRO￿mode￿ConnectedShift￿is￿not￿available.￿ConnectedShift￿is￿also￿not available￿during￿control￿operation￿of￿cruise￿control.

ConnectedShift￿is￿used￿in￿the￿F48,￿depending￿on￿the￿equipment,￿specifically￿in￿vehicles￿with￿gas engine,￿automatic￿transmission￿and￿navigation￿system.

A￿prerequisite￿is￿that￿the￿map￿data￿and￿the￿required￿additional￿information￿for￿the￿country￿are￿available. This￿is￿dependent￿on￿the￿navigation￿map￿provider￿and￿is￿not￿available￿worldwide￿for￿all￿countries.

12 F48￿Powertrain 3.￿Automatic￿Transmission

3.8.￿Notes￿for￿Service

3.8.1.￿Special￿tools

Two￿new￿diagnostic￿cables￿were￿designed￿for￿the￿automatic￿transmission￿as￿special￿tools:

• Adapter￿cable￿15-pin:￿83 30 2 352 734 • Adapter￿cable￿33-pin:￿83 30 2 352 718

3.8.2.￿Manually￿unlocking￿the￿drive￿position￿lock

F48￿Manually￿unlocking￿the￿drive￿position￿lock

If￿the￿gear￿selector￿switch￿is￿blocked￿in￿selector￿lever￿position P￿despite￿the￿ignition￿being￿switched on,￿brake￿being￿applied￿and￿the￿Unlock￿button￿being￿pressed,￿the￿drive￿position￿lock￿can￿be￿manually unlocked.￿There￿is￿a￿release￿lever￿under￿the￿sleeve￿for￿the￿gear￿selector￿switch,￿which￿can￿be￿operated using￿the￿screwdriver￿from￿the￿toolkit,￿for￿example.

13 F48￿Powertrain 3.￿Automatic￿Transmission

3.8.3.￿Available￿replacement￿parts

The￿following￿components￿of￿the￿automatic￿transmission￿are￿created￿as￿replacement￿parts￿in￿addition to￿various￿retaining￿and￿sealing￿elements:

• Cable￿holder￿(at￿transmission￿housing) • Gearshift￿lever￿(at￿gearshift￿shaft) • Electronic￿transmission￿control￿(EGS) • Oil￿filler￿plug • Electrical￿wiring￿set • Gearbox￿input-speed￿sensor • Hydraulic￿shift￿unit • Cover￿(hydraulic￿shift￿unit) • Transmission￿oil￿cooler • Oil￿drain￿plug￿(with￿overflow) • Torque￿converter • Radial￿shaft￿seals￿for￿transmission￿input￿shaft, as￿well￿as￿left￿and￿right￿axle￿shaft

14 F48￿Powertrain 4.￿xDrive

4.1.￿Introduction

The￿all-wheel￿drive￿system￿in￿the￿F48￿was￿redeveloped￿and￿for￿the￿first￿time￿at￿BMW.￿Although￿this all-wheel￿drive￿system￿is￿also￿called￿xDrive,￿it￿is￿considerably￿different￿from￿the￿versions￿previously installed,￿which￿were￿based￿on￿a￿rear-wheel￿drive.

The￿differences￿of￿the￿xDrive￿versions￿are￿listed￿in￿the￿following￿section.

4.1.1.￿Comparison￿of￿all-wheel￿drive￿systems

The￿following￿graphic￿shows￿the￿all-wheel￿drive￿system￿of￿the￿F48￿compared￿to￿the￿F25.

Comparison￿of￿the￿all-wheel￿drive￿system:￿F25￿–￿F48

Index Explanation A Four-wheel￿drive￿F25 B Four-wheel￿drive￿F48 1 Front￿axle￿differential 2 Automatic￿transmission

15 F48￿Powertrain 4.￿xDrive

Index Explanation 3 Transfer￿box 4 Rear￿axle￿differential 5 Angular￿gearbox 6 Longitudinal￿torque￿distribution￿(integrated￿in￿the￿rear￿axle￿differential)

The￿following￿table￿shows￿the￿key￿differences￿of￿the￿all-wheel￿drive￿systems￿in￿the￿F25￿and￿in￿the￿F48.

F25 F48 Longitudinal￿torque DSC DSC distribution￿requirement (setpoint￿torque) Control￿of￿the￿longitudinal VTG￿control￿unit Longitudinal￿torque torque￿distribution distribution￿control￿unit Longitudinal￿torque Multidisc￿clutch Multidisc￿clutch￿of￿the distribution in￿the￿transfer￿box longitudinal￿torque￿distribution Drive￿torque￿when 100 %￿at￿rear￿axle 100 %￿at￿front￿axle multidisc￿clutch￿open Activation￿of￿multidisc Via￿electric￿motor￿and￿ball￿ramp Via￿EHPS￿and￿hydraulic clutch operating￿pressure

The￿new￿all-wheel￿drive￿system￿with￿longitudinal￿torque￿distribution￿clutch￿has￿the￿following advantages￿in￿comparison￿to￿the￿all-wheel￿drive￿system￿with￿transfer￿box:

• Low￿space￿requirement • Low￿weight • Low￿splashing￿losses￿in￿the￿multidisc￿clutch￿(thanks￿to￿"Efficient￿mode")

• CO2￿reduction

16 F48￿Powertrain 4.￿xDrive

4.2.￿System￿components

F48￿overview￿of￿four-wheel￿drive

Index Explanation A Driving￿power￿to￿the￿rear￿wheels B Driving￿power￿to￿the￿front￿wheels 1 Front￿wheel 2 Output￿shaft,￿front 3 Angular￿gearbox 4 Automatic￿transmission 5 Propeller￿shaft

17 F48￿Powertrain 4.￿xDrive

Index Explanation 6 Rear￿wheel 7 Output￿shaft,￿rear 8 Cross￿member 9 Rear￿axle￿differential￿(with￿integrated￿longitudinal￿torque￿distribution)

With￿xDrive￿some￿of￿this￿driving￿power￿is￿transmitted￿to￿the￿rear￿output￿shafts￿(7)￿via￿the￿angular gearbox (3),￿the￿propeller￿shaft (5)￿and￿the￿rear￿axle￿differential (9).￿The￿gear￿ratio￿in￿the￿angular gearbox￿is￿1.74 : 1￿and￿in￿the￿rear￿axle￿differential￿1 : 1.74.

The￿engine￿speed￿is￿increased￿and,￿at￿the￿same￿time,￿the￿torque￿is￿reduced,￿as￿a￿result￿of￿the￿ratio in￿the￿angular￿gearbox.￿The￿propeller￿shaft￿can￿therefore￿be￿designed￿with￿smaller￿dimensions.￿The weight￿reduction￿helps￿the￿fuel￿consumption￿and￿the￿fewer￿moving￿masses￿benefit￿the￿smooth running.

In￿the￿rear￿axle￿differential￿the￿ratio￿is￿then￿reversed,￿so￿that￿the￿same￿engine￿speed￿is￿applied￿to￿the front￿and￿rear￿output￿shafts.

4.2.1.￿Angular￿gearbox

F48￿Angular￿gearbox

Index Explanation A Driving￿power￿to￿the￿rear￿wheels B Driving￿power￿to￿the￿front￿wheels 1 Angular￿gearbox 2 Pinion￿shaft

18 F48￿Powertrain 4.￿xDrive

Index Explanation 3 Input￿shaft￿(hollow￿shaft)￿with￿crown￿wheel 4 Intermediate￿shaft 5 Output￿shaft,￿front￿right 6 Propeller￿shaft

The￿angular￿gearbox￿is￿located￿behind￿the￿engine￿and￿is￿secured￿at￿the￿automatic￿transmission￿and￿at the￿crankcase.￿It￿transmits￿some￿of￿the￿driving￿power￿to￿the￿propeller￿shaft￿and￿is￿designed￿as￿a￿single- stage,￿i.e.￿only￿has￿one￿fixed￿ratio.

The￿input￿shaft￿of￿the￿angular￿gearbox￿is￿designed￿as￿a￿hollow￿shaft￿and￿is￿connected￿directly￿to￿the differential￿housing￿of￿the￿front￿axle￿differential.￿The￿driving￿power￿is￿transmitted￿from￿the￿differential housing￿to￿the￿propeller￿shaft￿via￿the￿hollow￿shaft,￿the￿crown￿wheel￿and￿the￿pinion￿shaft.

As￿a￿power￿interruption￿in￿the￿angular￿gearbox￿is￿not￿possible,￿the￿propeller￿shaft￿is￿driven continuously￿via￿the￿pinion￿shaft￿during￿the￿journey.

Irrespective￿of￿this,￿the￿intermediate￿shaft￿is￿guided￿to￿the￿front￿right￿output￿shaft￿through￿the￿hollow shaft￿and￿the￿crown￿wheel￿in￿the￿angular￿gearbox.

19 F48￿Powertrain 4.￿xDrive

4.2.2.￿Propeller￿shaft

F48￿propeller￿shaft

Index Explanation A Connection￿to￿rear￿axle￿differential via￿flexible￿disc B Connection￿to￿angular￿gearbox￿via￿a￿fixed￿ball￿joint￿with￿flange￿and￿inlay￿nut C Propeller￿shaft￿center￿bearing￿with￿tripod￿joint 1 Inlay￿nut 2 Shift￿unit 3 Hexagon￿head￿(for￿slackening￿the￿inlay￿nut￿at￿the￿angular￿gearbox)

20 F48￿Powertrain 4.￿xDrive

The￿propeller￿shaft￿is￿responsible￿for￿transmitting￿driving￿power￿provided￿by￿the￿angular￿gearbox￿in￿the form￿of￿torque￿and￿engine￿speed￿to￿the￿rear￿axle￿differential.￿With￿help￿of￿the￿tripod￿joint,￿it￿offsets￿the deflection￿angle￿and￿linear￿variations￿resulting￿from￿the￿assembly￿movements.

In￿front￿of￿the￿propeller￿shaft￿center￿bearing￿is￿a￿hexagon￿head (3),￿at￿which￿the￿propeller￿shaft￿can￿be rotated.￿As￿a￿result,￿for￿left-hand￿drive￿vehicles￿there￿is￿the￿option￿to￿remove￿the￿propeller￿shaft￿from the￿angular￿gearbox,￿if￿the￿inlay￿nut￿(1)￿is￿held￿over￿the￿right￿wheel￿arch￿at￿the￿same￿time.

In￿the￿F48￿with￿four-wheel￿drive,￿the￿currently￿longest￿propeller￿shaft￿of￿all￿current￿BMW￿models￿is installed.￿It￿is￿2.2 m￿long.￿It￿is￿designed￿as￿a￿two-piece￿tubular￿shaft￿and￿is￿secured￿to￿the￿body￿in￿the area￿of￿the￿middle￿joint￿via￿the￿flexible￿center￿mount.

The￿propeller￿shaft￿can￿be￿bent￿a￿maximum￿of￿10°.￿Otherwise,￿the￿gaiter￿in￿the￿tripod￿joint￿will￿incur damage￿

Support￿the￿propeller￿shaft￿during￿removal￿and￿installation￿and￿secure￿the￿gaiter￿with￿anti-kink protection.￿It￿is￿imperative￿the￿current￿repair￿instructions￿are￿observed￿when￿working￿at￿the￿propeller shaft.

F48￿Shift￿unit￿of￿the￿propeller￿shaft

21 F48￿Powertrain 4.￿xDrive

Index Explanation 1 Outer￿pipe￿(in￿direction￿of￿travel,￿rear) 2 Shift￿unit 3 Inner￿pipe￿(in￿direction￿of￿travel,￿front) 4 Coating￿(to￿achieve￿a￿defined￿low￿static￿friction￿force) 5 Shift￿direction

In￿the￿front￿propeller￿shaft￿sections,￿two￿contoured￿pipe￿sections￿are￿inserted￿in￿one￿another. The￿contour￿of￿the￿two￿pipe￿sections￿means￿it￿is￿possible￿to￿transfer￿the￿drive￿torque.￿In￿addition,￿the two￿pipe￿sections￿can￿be￿adjusted￿towards￿each￿other,￿whereby￿a￿coating￿generates￿a￿defined￿friction force￿of￿20 kN.

In￿the￿event￿of￿a￿front-end￿collision,￿a￿counterforce￿of￿maximum￿20 kN￿is￿generated,￿so￿that￿an additional￿load￿path￿is￿not￿created.

Following￿an￿accident,￿the￿shift￿unit￿of￿the￿propeller￿shaft￿must￿be￿checked.￿If￿the￿two￿pipe￿sections have￿shifted￿into￿one￿another,￿the￿propeller￿shaft￿must￿be￿replaced.￿The￿criteria￿for￿checking￿and replacing￿specified￿in￿the￿repair￿instructions￿are￿to￿be￿complied￿with￿precisely.

22 F48￿Powertrain 4.￿xDrive

4.2.3.￿Rear￿axle￿differential

F48￿Rear￿axle￿differential

Index Explanation 1 Bearing￿(rear￿axle￿differential￿to￿rear￿axle￿support) 2 Rear￿axle￿differential 3 Cross￿member 4 Bearing￿(cross￿member￿to￿body)

The￿rear￿axle￿differential￿in￿the￿F48￿with￿four-wheel￿drive￿is￿secured￿at￿the￿front￿to￿the￿rear￿axle￿support and￿at￿the￿rear￿to￿an￿additional￿cross￿member.￿In￿order￿to￿decouple￿noises￿and￿vibrations￿of￿the￿drive train￿from￿the￿vehicle￿body,￿both￿the￿rear￿axle￿differential￿at￿the￿rear￿axle￿support,￿and￿the￿additional cross￿member￿at￿the￿body,￿are￿secured￿via￿rubber￿mountings.

23 F48￿Powertrain 4.￿xDrive

Longitudinal￿torque￿distribution

F48￿Longitudinal￿torque￿distribution

Index Explanation 1 Multidisc￿clutch 2 Vent￿valve 3 "Efficient￿valve" 4 Input￿shaft 5 Input￿flange 6 Clutch￿housing 7 EHPS 8 Electrical￿line 9 Longitudinal￿torque￿distribution￿(LMV)￿control￿unit

The￿longitudinal￿torque￿distribution￿in￿the￿F48￿distributes￿the￿drive￿torque￿variably￿to￿the￿front￿axle￿and rear￿axle.￿It￿comes￿from￿the￿industrial￿modular￿system￿of￿the￿5th￿generation￿of￿the￿Haldex￿system￿from BorgWarner.

24 F48￿Powertrain 4.￿xDrive

Both￿the￿longitudinal￿torque￿distribution￿control￿unit￿and￿the￿EHPS￿pump￿unit￿are￿secured￿at￿the￿side at￿the￿transmission.

The￿longitudinal￿torque￿distribution￿clutch￿is￿integrated￿in￿the￿rear￿axle￿differential.￿The￿input￿shaft￿is driven￿by￿the￿propeller￿shaft￿via￿the￿input￿flange.￿The￿output￿flange￿drives￿the￿differential,￿depending on￿requirements.

25 F48￿Powertrain 4.￿xDrive

4.2.4.￿System￿wiring￿diagram

F48￿system￿wiring￿diagram￿for￿longitudinal￿torque￿distribution

26 F48￿Powertrain 4.￿xDrive

Index Explanation 1 Digital￿Motor￿Electronics￿(DME) 2 Electronic￿Power￿Steering￿(EPS) 3 Dynamic￿Stability￿Control￿(DSC) 4 Power￿distribution￿box,￿passenger￿compartment 5 Body￿Domain￿Controller￿(BDC) 6 K-CAN￿terminator 7 Actuator,￿longitudinal￿torque￿distribution 8 Longitudinal￿torque￿distribution￿control￿unit￿(LMV)

4.3.￿Function

4.3.1.￿Longitudinal￿torque￿distribution

F48￿clutch,￿longitudinal￿torque￿distribution

27 F48￿Powertrain 4.￿xDrive

Index Explanation 1 Input￿flange 2 Input￿shaft 3 Vent￿valve 4 Working￿piston 5 Axial￿needle￿bearing 6 Axial￿needle￿bearing 7 Output￿flange 8 Multidisc￿clutch 9 "Efficient￿valve"

Depending￿on￿the￿driving￿situation,￿the￿longitudinal￿torque￿distribution￿can￿direct￿some￿of￿the￿driving power￿(up￿to￿maximum￿torque￿of￿1300 Nm)￿to￿the￿rear￿axle,￿sometimes￿before￿the￿wheels￿even￿spin.

The￿DSC￿sends￿information￿about￿the￿clutch￿torque￿to￿be￿adjusted￿to￿the￿BDC￿via￿FlexRay￿and￿to the￿longitudinal￿torque￿distribution￿control￿unit￿via￿the￿K‑CAN3.￿The￿longitudinal￿torque￿distribution control￿unit￿controls￿the￿speed￿of￿the￿EHPS￿using￿pulse-width￿modulations.￿Depending￿on￿the￿speed, the￿EHPS￿applies￿an￿operating￿pressure￿of￿0￿to 40 bar￿to￿the￿clutch￿longitudinal￿torque￿distribution.

The￿pressure￿is￿not￿measured￿by￿a￿pressure￿sensor,￿but￿checked￿via￿a￿voltage/current￿comparison.

In￿driving￿situations￿in￿which￿the￿four-wheel￿drive￿is￿not￿required,￿the￿system￿switches￿to￿"Efficient mode".￿The￿"Efficient￿valve"￿lowers￿the￿oil￿level￿in￿the￿clutch,￿thus￿reducing￿the￿splashing￿losses.￿If￿the four-wheel￿drive￿is￿required￿again,￿the￿maximum￿torque￿can￿be￿provided￿within￿250 ms.￿The￿spring- loaded￿"Efficient￿valve"￿is￿operated￿by￿the￿oil￿pressure.

Adaptations,￿which￿monitor￿the￿system￿behavior￿and￿ensure￿position￿precision,￿are￿constantly performed￿in￿the￿longitudinal￿torque￿distribution￿control￿unit.￿A￿calibration￿is￿performed￿once￿during the￿driving￿cycle￿(terminal￿15￿ON)￿and￿stored.

Together￿with￿the￿calibration,￿a￿system￿ventilation￿is￿also￿carried￿out.￿The￿pressure￿is￿increased￿briefly to￿approximately￿45 bar￿in￿order￿to￿open￿the￿vent￿valve.￿The￿ventilation￿procedure￿guarantees￿quick pressure￿build-up￿in￿every￿regulating￿situation.

28 F48￿Powertrain 4.￿xDrive

4.3.2.￿Operating￿strategy

The￿operating￿strategy￿ensures￿that￿the￿four-wheel￿drive￿is￿operated￿as￿required￿and￿in￿an￿energy efficient￿manner.￿The￿traction￿requirement￿is￿detected￿in￿a￿proactive￿manner￿and￿the￿drive￿torque redirected￿accordingly.

In￿most￿driving￿situations￿only￿the￿front￿wheels￿are￿driven.￿Only￿in￿certain￿situations￿is￿some￿of￿the drive￿torque￿also￿transmitted￿to￿the￿rear￿wheels.￿The￿distribution￿of￿the￿drive￿torque￿between￿the front￿and￿rear￿wheels￿is￿defined￿by￿the￿DSC.￿The￿following￿criteria￿are￿taken￿into￿account:

• Speed • Lateral￿and￿longitudinal￿acceleration • Brake￿control • Steering￿angle • Wheel￿speeds • Vehicle￿longitudinal￿inclination • Pedal￿sensor￿position • Active￿driving￿program￿(SPORT,￿COMFORT,￿ECO￿PRO) • DSC￿status￿(DSC￿activated/deactivated,￿DTC￿activated/deactivated)

Depending￿on￿the￿driving￿situation,￿some￿of￿the￿drive￿torque￿is￿transmitted￿to￿the￿rear￿wheels. The￿exact￿ratio￿of￿the￿torque￿distribution￿is￿dependent￿on￿the￿activation￿of￿the￿multidisc￿clutch, as￿well￿as￿the￿slip￿of￿the￿wheels.￿Some￿factors￿on￿the￿activation￿of￿the￿multidisc￿clutch￿are￿listed￿below.

The￿four-wheel￿drive￿is￿activated￿in￿the￿following￿situations,￿if￿there￿are￿no￿other￿criteria￿present￿which prevent￿this:

• Understeering￿vehicle • Increased￿difference￿in￿speed￿between￿front￿and￿rear￿wheels • Large￿vehicle￿longitudinal￿inclination￿(e.g.￿on￿inclines) • Kick-down￿position • Sporty￿driving￿style • Respective￿environmental￿conditions,￿roadway￿conditions￿and￿type￿of￿terrain

The￿four-wheel￿drive￿is￿switched￿off￿in￿the￿following￿situations,￿if￿there￿are￿no￿other￿criteria￿present which￿prevent￿this:

• Large￿steering￿angle￿and￿driving￿speeds • Strong￿braking￿(ABS)

To￿assess￿the￿road￿condition￿and￿thus￿for￿effective,￿proactive￿longitudinal￿torque￿distribution,￿the coefficients￿of￿friction￿between￿the￿tires￿and￿roadway￿are￿calculated￿by￿the￿DSC.￿The￿wheel￿slip, as￿well￿as￿the￿longitudinal￿and￿lateral￿acceleration,￿are￿evaluated.

29 F48￿Powertrain 4.￿xDrive

If￿wheel￿speed￿information￿received￿by￿the￿DSC￿suggests￿different￿tire￿rolling￿circumferences￿of￿the wheels￿(e.g.￿for￿tires￿with￿varying￿degrees￿of￿wear),￿the￿multidisc￿clutch￿is￿no￿longer￿closed￿100 %. Differences￿in￿speed,￿resulting￿from￿different￿wheel￿speeds￿at￿the￿front￿and￿rear￿axle,￿are￿reduced￿in this￿case￿via￿the￿multidisc￿clutch,￿so￿that￿high￿torques￿are￿not￿transmitted￿to￿the￿drive￿train.

As￿the￿multidisc￿clutch￿is￿not￿closed￿100 %￿in￿this￿situation,￿the￿maximum￿transmittable￿drive￿torque to￿the￿rear￿axle￿is￿reduced.

4.4.￿Notes￿for￿Service

• The￿propeller￿shaft￿must￿be￿removed￿when￿working￿on￿the￿brake￿test￿stand. • When￿working￿on￿the￿brake￿test￿stand,￿all-wheel￿drive￿vehicle-specific￿points￿do￿not￿have￿to￿be observed￿(the￿test￿stand￿mode￿for￿checking￿the￿brake￿system￿is￿automatically￿detected). • The￿vehicle￿cannot￿be￿towed￿away￿if￿only￿one￿axle￿is￿raised. • Both￿the￿angular￿gearbox￿and￿the￿rear￿axle￿differential￿have￿an￿oil￿filling￿that￿lasts￿the￿entire service￿life￿of￿the￿assembly. • Using￿the￿diagnosis￿system,￿both￿the￿mechanics￿and￿the￿tightness￿of￿the￿EHPS￿can￿be checked￿(here￿the￿pressure￿is￿checked￿via￿a￿voltage/current￿comparison). • In￿order￿to￿remove￿the￿angular￿gearbox,￿the￿starter￿motor￿also￿has￿to￿be￿removed. • Similar￿to￿the￿previous￿all-wheel￿drive￿system,￿tires￿with￿very￿different￿tread￿depths￿cannot￿be used￿at￿the￿front￿and￿rear￿axle. • The￿maximum￿permissible￿deflection￿angle￿of￿the￿propeller￿shaft￿cannot￿be￿exceeded.

30 F48￿Powertrain 5.￿Output￿Shaft,￿Front

F48￿Output￿shafts,￿front

Index Explanation B F48￿with￿four-wheel￿drive 1 Output￿shaft,￿front￿left 2 Intermediate￿shaft 3 Output￿shaft,￿front￿right

The￿left￿output￿shaft￿is￿designed￿as￿a￿single￿piece.￿The￿right￿output￿shaft￿consists￿of￿an￿intermediate shaft￿at￿the￿engine￿and￿the￿actual￿right￿output￿shaft.￿Both￿output￿shafts￿are￿roughly￿the￿same￿length and￿have￿similar￿torsional￿rigidity.

The￿front￿output￿shafts￿are￿designed￿according￿to￿the￿maximum￿transmittable￿torque,￿in￿order￿to achieve￿minimal￿component￿weight.

The￿transmission-end￿tripod￿joints￿offset￿differences￿in￿length￿and￿deflection￿angles,￿the￿wheel- side￿fixed￿ball￿joints￿only￿offsets￿the￿deflection￿angles.￿The￿interfaces￿for￿the￿transmission￿or￿the intermediate￿shaft￿are￿defined￿as￿a￿journal￿solution￿and￿are￿designed￿depending￿on￿the￿respective transmission.￿The￿interface￿for￿the￿wheels￿is￿designed￿as￿a￿spur￿gearing￿solution￿and￿is￿identical for￿all￿sizes.

31 F48￿Powertrain 5.￿Output￿Shaft,￿Front

Comparison￿of￿front￿output￿shafts￿for￿vehicles￿with￿four-wheel￿drive:￿F25￿–￿F48

Index Explanation A F25 B F48 1 Output￿shaft,￿front 2 Angular￿gearbox 3 Transmission 4 Output￿shaft,￿front 5 Oil￿sump 6 Front￿axle￿differential

Due￿to￿the￿transversal￿installation￿of￿the￿engine￿and￿transmission,￿in￿the￿F48￿the￿front￿output￿shafts￿no longer￿have￿to￿be￿guided￿by￿the￿oil￿sump,￿as￿for￿example￿in￿the￿BMW X3 xDrive.￿In￿vehicles￿with￿a￿four- wheel￿drive,￿however,￿the￿front￿right￿output￿shaft￿is￿guided￿by￿the￿angular￿gearbox.

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